Influence of carbon and nitrogen sources on antifungal metabolite production by bacterium associated with entomopathogenic nematode against Penicillium expansum

A specific symbiotic Bacillus sp. isolated from a rhabditid entomopathogenic nematode, Rhabditis (Oscheius) sp. was found to produce large number of bioactive compounds. The present study was conducted to determine the effect of carbon and nitrogen sources for the production of antimicrobial substances by Bacillus sp. The yield of the crude antimicrobial substances and antimicrobial activity against the test micro-organism also differed significantly when carbon and nitrogen sources in the fermentation media were changed. The antifungal activity was significantly high in yeast extract plus fructose (46.5?±?2.12?mm) followed by yeast extract plus maltose, beef extract plus fructose and meat infusion plus glucose. High pressure liquid chromatography analysis of the crude antimicrobial substances revealed different peaks with different retention time indicating that they produced different compounds. When the carbon source was not included in the fermentation media, the antimicrobial production was substantially reduced. The results indicate that carbon source in the fermentation media plays a vital role in the production of antifungal substances. It is concluded that yeast extract and fructose as nitrogen and carbon sources produced maximum activity, which can effectively control the blue mould caused by Penicillium expansum in apples and pears.     

Dietary supplementation with docosahexaenoic acid, but not eicosapentaenoic acid, dramatically alters cardiac mitochondrial phospholipid fatty acid composition and prevents permeability transition

Treatment with the ω-3 polyunsaturated fatty acids (PUFAs) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) exerts cardioprotective effects, and suppresses Ca²⁺-induced opening of the mitochondrial permeability transition pore (MPTP). These effects are associated with increased DHA and EPA, and lower arachidonic acid (ARA) in cardiac phospholipids. While clinical studies suggest the triglyceride lowering effects of DHA and EPA are equivalent, little is known about the independent effects of DHA and EPA on mitochondria function. We compared the effects of dietary supplementation with the ω-3 PUFAs DHA and EPA on cardiac mitochondrial phospholipid fatty acid composition and Ca²⁺-induced MPTP opening. Rats were fed a standard lab diet with either normal low levels of ω-3 PUFA, or DHA or EPA at 2.5% of energy intake for 8 weeks, and cardiac mitochondria were isolated and analyzed for Ca²⁺-induced MPTP opening and phospholipid fatty acyl composition. DHA supplementation increased both DHA and EPA and decreased ARA in mitochondrial phospholipid, and significantly delayed MPTP opening as assessed by increased Ca²⁺ retention capacity and decreased Ca²⁺-induced mitochondria swelling. EPA supplementation increased EPA in mitochondrial phospholipids, but did not affect DHA, only modestly lowered ARA, and did not affect MPTP opening. In summary, dietary supplementation with DHA but not EPA, profoundly altered mitochondrial phospholipid fatty acid composition and delayed Ca²⁺-induced MPTP opening.     

Myocardial antioxidant status and oxidative stress after combined action of exercise training and ethanol in two different age groups of male albino rats

The interaction of exercise training and ethanol on the myocardial antioxidant enzymes and the oxidative stress markers was investigated in the Wistar strain male albino rats. We also tested the interactive effects of exercise training and ethanol on the age-associated free radical production and antioxidant defense system. We found a significant decrease (p<0.05) in the activity levels of superoxide dismutase (SOD) and catalase (CAT) in the myocardium of old rats when compared to young rats by 26% and 58%, respectively, suggesting the onset of age-dependent decrease in the myocardial antioxidant enzyme system. In contrast to the decreased antioxidant enzyme activity, xanthine oxidase (XOD) and lipid peroxidation (LPO) levels were elevated, suggesting the age-induced oxidative stress. Exercise training significantly (p < 0.05) elevated the activities of SOD, CAT, XOD and LPO levels in both the age groups of animals. Ethanol consumption significantly lowered the SOD and CAT activities in both the age groups, whereas a significant increase was observed in the XOD and LPO levels. In contrast, the combination of exercise training plus ethanol lowered XOD and LPO levels in both the age groups of rats compared to ethanol treated rats. A significant (p < 0.05) increase in the activities of SOD and CAT was reported in the rats treated with the combination of exercise training plus ethanol. This increase was more pronounced in the younger rats than the older rats. The findings of the present investigation on the potential role of antioxidant enzymes to counter the ethanol-induced pro-oxidants showed an increase with the interaction of exercise training. With age, a decrease in the antioxidant enzyme capacity was observed. This reveals that the old age rats were more affected to the pro-oxidants when compared to the young age rats. In conclusion it is demonstrated that two months treadmill endurance exercise training is beneficial to both young and old rats in improving antioxidant defense to challenge the oxidative stress in the myocardial tissue and thereby successfully countering the free radical production due to ethanol intoxication.     

Warming and drought differentially influence the production and resorption of elemental and metabolic nitrogen pools in Quercus rubra

The process of nutrient retranslocation from plant leaves during senescence subsequently affects both plant growth and soil nutrient cycling; changes in either of these could potentially feed back to climate change. Although elemental nutrient resorption has been shown to respond modestly to temperature and precipitation, we know remarkably little about the influence of increasing intensities of drought and warming on the resorption of different classes of plant metabolites. We studied the effect of warming and altered precipitation on the production and resorption of metabolites in Quercus rubra. The combination of warming and drought produced a higher abundance of compounds that can help to mitigate climatic stress by functioning as osmoregulators and antioxidants, including important intermediaries of the tricarboxylic acid (TCA) cycle, amino acids including proline and citrulline, and polyamines such as putrescine. Resorption efficiencies (REs) of extractable metabolites surprisingly had opposite responses to drought and warming; drought treatments generally increased RE of metabolites compared to ambient and wet treatments, while warming decreased RE. However, RE of total N differed markedly from that of extractable metabolites such as amino acids; for instance, droughted plants resorbed a smaller fraction of elemental N from their leaves than plants exposed to the ambient control. In contrast, plants in drought treatment resorbed amino acids more efficiently (>90%) than those in ambient (65–77%) or wet (42–58%) treatments. Across the climate treatments, the RE of elemental N correlated negatively with tissue tannin concentration, indicating that polyphenols produced in leaves under climatic stress could interfere with N resorption. Thus, senesced leaves from drier conditions might have a lower nutritive value to soil heterotrophs during the initial stages of litter decomposition despite a higher elemental N content of these tissues. Our results suggest that N resorption may be controlled not only by plant demand, but also by climatic influences on the production and resorption of plant metabolites. As climate–carbon models incorporate increasingly sophisticated nutrient cycles, these results highlight the need to adequately understand plant physiological responses to climatic variables.     

Excessive hepatic mitochondrial TCA cycle and gluconeogenesis in humans with nonalcoholic fatty liver disease

Approximately one-third of the U.S. population has nonalcoholic fatty liver disease (NAFLD), a condition closely associated with insulin resistance and increased risk of liver injury. Dysregulated mitochondrial metabolism is central in these disorders, but the manner and degree of dysregulation are disputed. This study tested whether humans with NAFLD have abnormal in vivo hepatic mitochondrial metabolism. Subjects with low (3.0%) and high (17%) intrahepatic triglyceride (IHTG) were studied using (2)H and (13)C tracers to evaluate systemic lipolysis, hepatic glucose production, and mitochondrial pathways (TCA cycle, anaplerosis, and ketogenesis). Individuals with NAFLD had 50% higher rates of lipolysis and 30% higher rates of gluconeogenesis. There was a positive correlation between IHTG content and both mitochondrial oxidative and anaplerotic fluxes. These data indicate that mitochondrial oxidative metabolism is ~2-fold greater in those with NAFLD, providing a potential link between IHTG content, oxidative stress, and liver damage.     

Genome-wide evaluation of histone methylation changes associated with leaf senescence in Arabidopsis

Leaf senescence is the orderly dismantling of older tissue that allows recycling of nutrients to developing portions of the plant and is accompanied by major changes in gene expression. Histone modifications correlate to levels of gene expression, and this study utilizes ChIP-seq to classify activating H3K4me3 and silencing H3K27me3 marks on a genome-wide scale for soil-grown mature and naturally senescent Arabidopsis leaves. ChIPnorm was used to normalize data sets and identify genomic regions with significant differences in the two histone methylation patterns, and the differences were correlated to changes in gene expression. Genes that showed an increase in the H3K4me3 mark in older leaves were senescence up-regulated, while genes that showed a decrease in the H3K4me3 mark in the older leaves were senescence down-regulated. For the H3K27me3 modification, genes that lost the H3K27me3 mark in older tissue were senescence up-regulated. Only a small number of genes gained the H3K27me3 mark, and these were senescence down-regulated. Approximately 50% of senescence up-regulated genes lacked the H3K4me3 mark in both mature and senescent leaf tissue. Two of these genes, SAG12 and At1g73220, display strong senescence up-regulation without the activating H3K4me3 histone modification. This study provides an initial epigenetic framework for the developmental transition into senescence.     

Rhamnolipid biosurfactants: evolutionary implications,applications and future prospects from untapped marine resource

Rhamnolipid-biosurfactants are known to be produced by the genus Pseudomonas, however recent literature reported that rhamnolipids (RLs) are distributed among diverse microbial genera. To integrate the evolutionary implications of rhamnosyl transferase among various groups of microorganisms, a comprehensive comparative motif analysis was performed amongst bacterial producers. Findings on new RL-producing microorganism is helpful from a biotechnological perspective and to replace infective P. aeruginosa strains which ultimately ensure industrially safe production of RLs. Halotolerant biosurfactants are required for efficient bioremediation of marine oil spills. An insight on the exploitation of marine microbes as the potential source of RL biosurfactants is highlighted in the present review. An economic production process, solid-state fermentation using agro-industrial and industrial waste would increase the scope of biosurfactants commercialization. Potential and prospective applications of RL-biosurfactants including hydrocarbon bioremediation, heavy metal removal, antibiofilm activity/biofilm disruption and greener synthesis of nanoparticles are highlighted in this review.